safe navigation (`&.`) をオペレータに対して実行したい safe navigation `[]` `+` nillable_int + 3 `[]` some_obj_not_responding_to_dig[:foo][:bar] safe navigation

`[]` `at`

`some_obj_not_responding_to_dig&.at(:foo)&.at(:bar)`

ruby
`def +()`
`lhs.+(rhs)`
safe navigation `lhs&.+(rhs)`

`[]`
`some_obj_not_responding_to_dig&.[](:foo)&.[](:bar)`
(`at`)